Problem: William bought a new backpack at the store when they were having a $40\%$ off sale. If the regular price of the backpack was $$35$, how much did William pay with the discount?
First, find the amount of the discount by multiplying the original price of the of the item by the discount. $$35$ $\times$ $40\%$ $=$ Percent means "out of one hundred," so $40\%$ is equivalent to $\frac{40}{100}$ which is also equal to $40 \div 100$ $40 \div 100 = 0.40$ Multiply the discount you just converted into a decimal by the original price to find the amount of money saved. $0.40$ $\times$ $$35$ $ = $ $$14.00$ Subtract the discount you just found from the original price to get the final price William paid. $$35$ $-$ $$14.00$ $ = $ $$21.00$ William paid $$21.00$ for the backpack.